27 February 2008

Number sense?

Numbers Guy, from the March 3, 2008 issue of The New Yorker, on human beings' intuitive "number sense".

Interestingly, we're quicker at comparing numbers that are further apart, which seems to imply some intuitive sense of "number line" -- and our number line perhaps has some sort of strange metric (not the usual one) in which the distance between 2 and 3 is longer than the distance between 7 and 8, since we're faster at saying 3 is larger than 2 than we are at saying 8 is larger than 7. (See, for example, yesterday's post on hyperbolic discounting which exploits a similar phenomenon with respect to timelines.)

And here's an interesting fact:

Because Chinese number words are so brief—they take less than a quarter of a second to say, on average, compared with a third of a second for English—the average Chinese speaker has a memory span of nine digits, versus seven digits for English speakers. (Speakers of the marvellously efficient Cantonese dialect, common in Hong Kong, can juggle ten digits in active memory.)